The current implementation in Chrome has two shortcomings - it requires the browser to be rebooted to detect device changes, and it doesn't yet support the connect/disconnect events. Both of those problems will be fixed, but right now, you can't do what you're trying to do. (AKA - you're understanding the spec correctly, but Chrome just doesn't do that yet. :)
UPDATE MAY 2015: Chrome 43 supports both of these properly, so as of version 43 you should be able to have these work as specified.